Method of measuring the elongation of hollow cables



Nov. 21 1933. G. ZAPF 1,936,282

METHOD OF MEASURING THE ELONGI LTIQN OF HOLLOW CABLES Filed 00%.. 13, 1930 Patented Nov. 21, 1933 I UNITED STATES PATENT OFFICE METHOD OF MEASURING THE ELONGATIONI F HOLLOW CABLES Georg Zapf, Cologne, Germany, assignor to Felten & Guilleaume Carlswerk Actien-Gesellschaft, Cologne-Mulheim, Germany Application October 13, 1930, Serial No. 488,461, and in Germany October 23, 1929 1 Claim. (Cl. 73-51) In carrying ropes, more particularly bridge capable of moving freely therein. When fixing ropes for suspension bridges, it is desirable to be in position a rope constructed according tothe able to determine the extension which occurs invention, the measuring wire disposed within it when the ropes are subjected to load. Determimay, for facilitating the measurement of exten- 5 nations by subsequent measurement of the length' sion, be fixed together with one end of the rope, i

of the rope under load and a comparison of this while at the other end of the rope the measuring length of the rope with its length before the wire, which must of course be longer than the application of the load involve a considerable rope to be measured, is passed freely through amount of trouble and, in the case of great lengths the fixing place. This last-named end of the rope 10 of rope, are very inaccurate. I is shown in Fig. 2.

The present invention relates to a wire rope That portion of the measuring wire, by which which is provided with an arrangement which the measuring wire is longer than the rope, is makes it possible to determine the extension of suitably marked with a scale, so that, on the rope the wire rope which takes place under the infiubeing loaded, the extension of the rope can be 15 ence of the load without any separate measuring read off directly on the measuring wire. The devices directly on the loaded rope itself. For material used for the measuring wire is preferthis purpose measuring wire preferably of steel, ably one in which the expansion due to heat is similar to a piano wire is provided in the interior very small, for instance invar. of the rope, so as to be free from friction and It should be remarked that the construction of 20 independent of the rope wires surrounding it, such the wire shown in the drawing is only given as that, on the rope being placed under load, it an example and that other constructional forms takes up no part of the load. As this wire retains are possible if they fulfill the condition that the its original length, even when the rope is loaded, measuring wire is so disposed in them as to be the difference in length between the measuring as free from friction as possible. Thus, for-in- 25 wire within the rope and the rope itself gives the stance, the space in the interior of the rope for extension which has taken place under the infiucontaining the measuring wire may also be pro ence of a load. For providing the requisite clearduced by forming the core of therope of round ance for the measuring wire, the rope is made wires, which enclose a gusset-shaped space. hollow. If the measuring wire intended'to be disposed 30 One possible constructional form of the measin the interior of the rope is to be introduced uring arrangement is illustrated in the accomsubsequently, it will be found of advantage to panying drawing. Fig. 1 shows a section through cause it to rotate at a high speed of revolution the rope with the measuring wire within it and for facilitating its insertion. Fig. 2 is a side view showing the arrangement of What I claim is': c

35 the separate parts. a is the hollow rope, b one A method of measuring the extension of a end of the same and c the measuring wire. The hollow wire rope under load, consisting in introhollow space within the rope for the reception ducing into the interior of the hollow wire rope of the measuring wire is produced by the core ofa measuring wire capable of sliding freely in said the rope having the form of a hollow rope made interior, loading the rope without subjecting the 40 of separate profiled wires, for instance wires hav said wire to load and measuring thedi f ce in ing a section of the form of a 'sector of an annulus, length between the loaded wire rope and the which abut against one another. The measuring measuring wire in the interior thereof.

wire is disposed in this hollow space so as to be G. ZAPF. 

